Stabilization of polyfluorophosphazenes with zinc hippurate

Abstract

When polyphosphazenes are exposed to elevated temperatures, their physical properties deteriorate. The addition of zinc bis hippurate to polyphosphazene rubbers has been found to result in improved retention of the physical properties of polyphosphazenes. Further the use of such an additive does not adversely affect the ability of peroxy compounds to cure the polyphosphazenes to form vulcanizates.

We claim: 
     
       1. A polyphosphazene composition stabilized against thermal aging comprising (1) a polyphosphazene represented by the general formula: ##STR4## wherein n represents an integer from 20 up to about 50,000 and X and X 1  each represent a monovalent substituent selected from the groups consisting of alkoxy, substituted alkoxy, aryloxy, substituted aryloxy, hydroxy, and amino, and X and X 1  are randomly distributed along the --P═N-- backbone and the polyphosphazene includes one or two or more randomly distributed groups, and (2) a stabilizer consisting of an organic compound compatible with said polyphosphazene and present in an amount sufficient to stabilize said polyphosphazene against thermal degradation, said organic compound being zinc bis hippurate. 
     
     
       2. The composition of claim 1 wherein the zinc bis hippurate is present in an effective amount up to 5.0% by weight. 
     
     
       3. The stabilized polyphosphazene composition of claim 1 wherein X and X 1  are fluoroalkoxy or fluoroaryloxy groups. 
     
     
       4. Elastomers containing essentially of the stabilized polyphosphazenes of claim 1. 
     
     
       5. Plastics consisting essentially of the stabilized polyphosphazenes of claim 1. 
     
     
       6. Thermoplastic elastomers consisting essentially of the stabilized polyphosphazenes of claim 1. 
     
     
       7. Fibers consisting essentially of the stabilized polyphosphazenes of claim 1. 
     
     
       8. Vulcanized articles consisting essentially of the stabilized polyphosphazenes of claim 1. 
     
     
       9. Peroxide cured polyphosphazene compositions of claim 1 in which from 0.2 to 0.5 percent of the groups X or X 1  are unsaturated. 
     
     
       10. The compositions of claim 9 in which the groups X and X 1  are trifluoroethoxy, OCH 2  (CF 2 ) y  CF 2  H and o-allylphenoxy in which y is either 1, 3, 5, 7 or 9 and mixtures thereof. 
     
     
       11. The composition of claim 10 in which the molar ratio in % of trifluoroethoxy to telomer fluoroalkoxy is between 70:30 and 30:70 and which contains in addition from 0.2 to 5.0 wt. % o-allylphenoxy groups.